Owners manual for Rinnai Waterless Hot water heater R85?

I installed and am now having a problem since yesterday with not getting hot water. But the next time I try I have hot water?? this has happened twice and I cannot find my manual to trouble shoot. I cannot locate the manual on their web site.

When I first run on the hot water only tap I have hot water. However shortly after I turn on the cold water tap the hot water goes completely cold. The unit is approximately two years old. rinnai r85 gas tankless

VR,When I first run on the hot water only tap I have hot water. However shortly after I turn on the cold water tap the hot water goes completely cold. The unit is approximately two years old. rinnai r85 gas tankless

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I just looked at the exploded drawing for the Manatee. It looks like a very simple heater. The heater will simply come on whenever the pump is running and the thermostat says that the tub is not hot enough. So, for the heater, set it and forget it.

The adjustment you can make is by setting the low-speed pump timer. There should be a timer on the control box, somewhere. Generally, you set the timer to come on for a couple of hours, twice a day. During those times, the pump will come on low-speed and the heater will come on as needed.
Keep in mind that the tub will only heat when the pump is running so you will want to set the timer so that the tub has been running for at least an hour when you will be ready to use it.

Most controls will also allow you to put the pump on thermostat control, usually with a switch (timer/ t-stat). By running on t-stat control, the low-speed pump and heater will turn on whenever the temperature drops a couple of degrees.

Timer control is usually more efficient for two reasons:
1. The tub doesn't heat water when you don't need it (like while you are sleeping or at work).
2. The pump isn't cycling on and off all day and night. Cycling is not very efficient.

Tip: If you want to soak when the tub isn't hot, just turn the pump on for 10 minutes or so before you get in. That is a pretty big heater, and unless you have very poor insulation or a worn-out cover, the temp shouldn't drop too fast.

Another tip: The best way to save money on a tub is to maintain your pH. Check it EVERY WEEK! Incorrect pH will shorten the life of your heater and seals. One service call would have paid for a lot of electricity.

There are 3 or 4 elements in there. One or more are bad. Just disconnect the wires and check for continuity. Check the thermostats too. The most common problem is sediment build up. If it is really bad you have to take the elements out and flush out the tank. Use Lime Away or similar product. Sometimes there can be so much build up there isn't room for the water and it will burn out the elements. This only has a 5 gallon tank so it doesn't takd much.

I don't know how high the water got but if only the burner was covered it is probably just dirt. Try replacing the thermocouple this is usually less than $10. If the gas valve itself was wet REPLACE THE WATER HEATER!!!!!!! Never trust a gas valve that has been wet!!!!! It can seem to work just fine but get stuck in the open position defeating all safety measures.